<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Ball</title>
    <link rel = "short icon" href=".\img\guan-cross.jpg"/>
    <style>

        .s1{
            width: 300px;
            height: 300px;
            /* 居中显示 */
            margin: auto;;
            background-color: white;
        }
        .s1:hover{
            border-radius:55%;
            box-shadow:inset 50px 30px 80px 30px rgba(55, 55, 55, 0.662);
        }
        .s1{
            transition: all 1s linear 0s;
        }
        .s2{
            width: 300px;
            height: 200px;
            background-color: rgb(201, 252, 201);
            /* 文本居中显示 */
            text-align: center;
            margin: auto;
        }

    </style>
</head>
<body>
    <div class="s1">
        <span class="s2">This is a ball</a></span>
    </div>
</body>
</html>